Newbie requires help: Desk for Track Mat (6ft x 4ft)

Try Scale Rail, they do custom baseboards to set sizes. I have no connection with them apart from being a very satisfied customer. A 6x4 is about £80 there, £95 with legs. The workmanship is very good.
Djo

Because its HUGE. A typical desk is only 2ft6 deep. I trust your flat is big.
Option 1 - find a custom furnature maker who will do cheap tables ('cos £200 is cheap for custom).
Option 2 - find a big dining table - Ikea will have something - , then add a sheet of board to the top, such as ply or MDF. The board will have to overlap in width by at least 6 inches each side because I doubt you'll find a 4ft wide table, but that will be OK. A large DIY shed will sell you the MDF cut to size. The weight of the board should hold it in place, but if really worried get someone to join it. If you want the edges finishing smartly, add picture framing timber to the edges.
Option 3 - dig around for someone offering custom baseboard building.
Option 4 - two identical small dining tables, one each end, supporting a MDF board.
Must be a few other ideas around...

I'd say TRY 6x4 is not big is easy to do with SIMPLE tools of saw screwdriver and hammer
and to throw £200 at a table top layout is silly money
-- Regards Gray
snipped-for-privacy@madcaravanner.uk