Lozza. Great. Good luck with it.
I think you'll be impressed.
Which type of kitchen are you thinking of (nosy)?
If Higham are only an hour from you, it will be handy. Devol are the other end of the country.
Email them your layout plan and they will cost it up for you. Much easier than doing it yourself.
You should look at appliances now because you can get ex display models in the sale half price. It's worth it because they've never been plugged in it actually used so as long as you've seen they have no scrapes on them you're quids in and can spend the saving elsewhere in the kitchen.
I bought the John Lewis fridge freezer with integrated wine fridge as ex display for 1/3 of its price. It had never been plugged in and we still got the 5 year warranty with John Lewis. It had a tiny scrape on the side which you can't see now its positioned inside the kitchen units.
I put the savings towards very expensive worktops and two stainless steel Smeg Piano ovens. 
Gucci. I had a quote from Plain English. Not quite the same layout as a ended up buying from Higham but a similar number of units and sizes. It was £65k excluding worktops, appliances etc. And that was for their southwold kitchen which is quite basic and built from tulip wood.
The Higham kitchen I got is the handlesless shaker with frames and rails built from solid maple with lacquered birch insides and that came to just over £23k. Obv exc appliances and worktops but inc fitting etc.
So a massive difference. I did love the Plain English but you're paying for their costly Marylebone and Shorditch showrooms.