2 x bucket £6
1 x Eurow sheep/lambswool mitt £7
Bilt Hamber Autowash £9 (only 5ml required a time so will last ages)
2 x Eurow waffle weave drying towels £19 (you can get by with one but two is better)
Bilt Hamber Autoclay £10 (uses water rather than dedicated lube, and is a bigger bar so works out cheaper)
Polish (see below)
Collinite 476s with 2 applicators and 3 microfibre cloths (see Elite Car Care) £19
AG Bumper Care £6
AG Fast Glass £6
Assorted cheap microfibres £3
In terms of polish it will depend on the condition of your paintwork (i.e. whether it needs swirls, scratches taking out, etc.). I'm sure the guys on here will recommend plenty of good products.
That all comes to £85. Add another £10 - £15 for quality polish and you're well on your way. The problem is when you get bitten by the bug you'll start longing after new stuff, then it gets expensive...