Could anyone recommend a mountain bike that will help an unfit cycler get fitter but doesn't break the budget?

Gel saddle covers are also a good investment. If your bike is out in the rain, the saddle cover need not be and you don't get a wet bum!

Womens specific geometry is just a marketing measure - what they actually are typically are relaxed frames, what in the mens range would be called "sportive" or "roubaix". This is because despite what everyone tells you, women in the UK actually have typically shorter legs and longer bodies than men, but regardless of that there's more difference between individuals than there is between the sexes.

What women do need though typically, are narrower handlebars (women do tend to have narrower shoulders) and different shaped seats. A local bike shop should be willing to change these for you when you buy (but they could be changed after and aren't that expensive.

With saddles, more padding is not necessarily a good thing, you need the right amount, bike shops will often have test saddles you can ride (often in very bright hideous colours) and you try them out to find the right shape for you.

Good advice from earlier posters. I would recommend a Spezialised Sirrus. Fab bike around £450if you buy an older model.

Ladies saddle always good but ladies geometry not necessarily. It depends on your proportions - for example I am a short arse but ride xs blokes frames due to my proportions. Is good for me as mucho bargains to be had in that size .

Get training and come to Stirling for Diva 100 race in May - is an easy route no big hills!

There are 2 independent bikes shops in Carlisle which have a good reputation and range of stock.scotby cycles and Palace cycles.

my best bike is seriously razor sharp on my little bottom - buts it isn't the bikes fault it is the saddle so I have padded shammy in my lycra shorts and I also have padded boxers to wear with normal shorts

Also my better bike is less hurty on the arse.

I bought my first bike from Decathlon less than a year ago, it was about £300 and a hybrid. I took to cycling even though I'm the least sporty person you could meet and found very quickly that it was a mistake to buy such a cheap bike even though it was the best one Decathlon did at the time. Within four months I went to my local independent bike shop and bought a good hybrid they were incredibly helpful. I'd skip the Decathlon route and go straight to your indi bike shop, don't be put off by the seriously expensive bikes the people that work there will just want to find the right bike for you and your budget. It's in their interest because when you get hooked and want another one you'll go back.

Good luck.

The Boardman range at Halfords get good reviews and will probably have a hybrid in your price range. Would definitely recommend a chat in a good local bike shop though.

Forgot to say one thing that makes a huge difference to the whole ass-hurting issue is padded shorts. They don't have to be tight Lycra, I've got a pair which have an inner padded layer with a pair of baggy outside shorts (I'm not describing it well). Anyway they work!

I'm currently looking at buying a bike as well. I haven't decided on what so can't advise on specific models (though tempted by a Giant Roam which is like a lean mountain bike, I think the guy called it an "urban cross" as far as I can tell a variation of hybrid.) Anyway I found the staff in Cycle Surgery generally know their stuff so you could go and chat to them even if you don't buy from there. They will tell you about the different types of hybrids etc. Also at the moment they have sales on so you can get last season's bikes for £50-£100 cheaper (though not as much choice obviously). And if you work then your company might be signed up to a cycle scheme which essentially allows you to buy a bike free of tax and NI (so it gets deducted from your gross earnings if that makes sense). Depending on tax bracket this can save you a bit as well. (Plus the employer saves money as well because they don't pay NI on the price of the bike.) Hope that helps a bit.

My hybrid was around £430 (Marin Muirwoods), 5 years ago.
I have it set up with MTB geometry (just means it's more aerodynamic than most hybrids).

Halfords is better than tesco, in that at least they do sell some pretty good bikes - yes the staff are very variable, but they have some good bikes at good prices, So especially if you can find a friend to make sure they put it together okay, and help you size it etc. then you'll be okay.

Decathlon are probably the only other bet, independant bike shops would be good too, but there you sometimes go the other way and even the cheapest bike would be too expensive (well more expensive than you need to spend)

A 2nd hand bike could be an option too, local to us we have a "recycles" bike shop which sells 2nd hand bikes done up nicely, if you had something similar it could be good - likely to have a more knowledgeable staff too.

I'd second finding a local cycle shop for the bike itself. You'll get good advice then, and they can do bike 'mot' to keep it in working order. For accessories like helmet/lights etc these may be cheaper online/halfords/Argos.

Halfords generally aren't great: is there a small bike shop (rather than car shop that sells a few bikes) near you?

If not, Halfords is much better than the likes of Tesco, but they don't have a great reputation (waits for someone to come along and disagree).

Just remembered, the Carrera Subway is well thought of (from Halfords) - however, the quality of Halfords bike staff is extremely variable; there are, apparantley, some Halfords staff who know a lot about bikes, but not many. I would advise taking a knowledgeable friend if going to Halfords, and getting them to check the bike after delivery as I have heard some horror stories about the way they have delivered bikes to customers...

Frame size can be roughly determined based on height and gender, leg length is better, but ideal is to go somewhere that will fit it properly - different frames (even the same size) will suit different back/arm length combinations; sometimes it can be adjusted by changing the stem.

But if I was spending that much I'd definitely want to go and try the bike and make sure it was comfortable for me.

you'll pick up a decent hybdrid easily on that budget. Ask for female specific saddles, preferably a touring saddle as it will support your arse bones. A good shop with adjust everything to your height and reach.

At that kind of budget I'd find a good local bike shop and go in there to try some bikes. Failing that Evans are pretty good and in most cities. The most important thing is that it fits and is well set-up - anything over £300 is likely to be pretty decent; anything under that need choosing with extreme caution...

I got a hybrid because mountain bikes are actually quite heavy and not that well suited to the type of cycling I wanted to do...mostly cycle and tow paths. You can get them in Halfords but I found the local independent cycle shops to be better value, competitive on price and good for after sales help and advice.