Radiators where and what to buy?

strawb_shortcake

We are doing some work in the house, and replacing the radiator in the bathroom with a heated towel rail (Central heated) and we want to go from a standard radiator to a grey two column one in the kitchen.
Having never bought either before, any recommendations on where to buy from and any suggested brands? 
Also when looking at radiators it isn't clear if you get everything you need - I assume I need to buy new valves too? 
We do have someone coming to do the work but I'd just like to have a better idea first. 
We aren't doing a hugely expensive redecorating job but would hope to spend upto £350 ish on a radiator and less than that on the towel rail - doesn't include labour costs
Thank you 

Mutton_Geoff

Radiators don't come with valves (unless there is an offer like Screwfix often run). You probably don't need a TRV in the bathroom, just basic valves will be fine for that room.

TELLIT01

Have a look on the Screwfix site or, better still, go round and pick up one of their catalogues.  They have great information in them.