Have a look at this site for inspiration... http://forkenswift.com
It shows what can be done with time and ingenuity!!!
I'm a newbie but I would suggest thinking carefully abut what you want the car to achieve in terms of range and performance. Have a lok throught the garage, top right hand side on the homeboy page, noting which motors/batteries/voltages have been used.
Very broadly, the higher he voltage of the battery pack the higher top speed. The range can be altered by the capacity of the battery pack (in Ah).
I started with chosing a motor suitable and then considered batteries. Lead acid, lithium, etc.
I would say that be prepared to have to spend quite a lot of time, effort and money to get what you want.
After all my deliberations and designs I stumbled across a previously converted car which needs work but managed to save a lot of time and effort. It had a good 9'' motor which was what I really wanted.
A good source of part information can be found by following the adverts on the right hand side of the pages on this site.
I'm in the UK too and parts are not quite so available as they are in the US.
Your shopping list is motor, controller, coupling, adaptor plate, batteries, charger, DC-DC converter (to run all the existing 12V equipment like lights, etc) or just use a dedicated 12V battery, throttle potentiometer....eerrrr....heater....eerrrrr....va cuum pump to run power brakes and/or steering as applicable....that should keep you busy!!!
Not cheap but you'll save in the long run...
Good luck and I'm happy to help, as far as I can.