£2k is a very good starting budget.
I would be inclined to spend £1k on the bike which will get you a quality aluminium frame with Shimano 105 from Cube, Giant or Boardman.
The same £1k will bag you a carbon bike with full Shimano Ultegra (even higher spec) from Planet X.
Aim then to get all your clothing & extras for £500.
If you shop around & buy last years designs & colours you can buy very good cycling kit @ good discounts from
www.chainreactioncycles.com www.ribblecycles.co.uk www.probikekit.com www.merlincycles.co.uk www.wiggle.co.uk &
www.evanscycles.co.uk
You will need 2 of some clothing items - 1 on & 1 in the wash, so..
1x good quality cycling lid
2x bibshorts
2x jerseys
1x pr cycling shoes
1 or 2x winter bib tights
4x socks
1x lightweight (packable) rain jacket
1x heavyweight winter rain jacket
1x summer Cycling gloves
1x winter Cycling gloves
Then...
V.good quality lock
Lights
mini/micro pocket pump
Track pump for home use
Puncture repair kit
2x Spare inner tubes (1 to take with you & 1 for home)
1x saddle bag (if you want to carry a spare tube, repair kit, mobile phone etc).
You could build all this stuff up as you spot good deals in sales but some of it is needed immediately.
Your cycling buddies should be able to help with other practicalities.
See if you can get on a basic maintenance course through a local bike shop or cycling club.
Most importantly of all, enjoy your cycling & the camaraderie of like minded friends.
