I think I want some sort of running watch GPS device but no idea what.

[SoPassRemarkable]

I would like the following features....

Constant heart rate monitoring
I'd like it to have some sort of GPs feature so it can log my runs for distance and time.

I would like it to have some sort of app or website where it will automatically sync and log run times and distances. I can't faff about with having to plug the watch into a laptop. I really need it to work with my iPad.

I would like it to have an altimeter so when I go hill walking I can use it then.
I would like when I'm running to be able to see how many mph I'm running at so I can pace myself.

I'd like to be able to input my treadmill run distances and times when I run inside.....either into the device or at least intonthe app so I can keep an accurate log of all my runs in a month.

Does such a thing exist?

Yes! Most basic running watches will have everything but the altimeter; for that you need the slightly fancier ones. Makes include Garmin, Tomtom and Suunto. A website called dcrainmaker (I think!) does good reviews, as do running &outdoor magazines such as Runners World

How accurate do you need each of those bits of info?
I only know that heart rates are most accurate with chest straps, not so trustworthy without straps.

I guess not overly accurate. Distance and time would be more accurate.

Was looking at the garmin 35 but now see the garmin 235 which looks prettier is on offer on amazon for today only.but not sure it's worth the extra.

yes the 235 ticks all your boxes, if you can afford it, it's worth it over the 35.

Sod it, going to get it. Thanks everyone.

I love my Garmin forerunner, very accurate, reliable and they look great (I wear it as my actual watch).

Is it the 235 you have? How long does the battery last?

I've got a 4 year old 620 so the 235 is better and my battery lasts ageessss. If I do a busy running week (30 miles and interval sessions), it'll keep going for the whole week. If I just use it as a watch (had a few weeks off running in early pregnancy), it'll last 3-4 weeks.
It's probably my favourite item I own!