DWC to the Marina/Palm area: not that far, probably in the 70AED range.

From DWC to the Downtown area or further north (Deira, Creek etc): a fair bit further, probably in the 120AED range, and may take 1h+ in traffic.

Both areas have nice hotels so you just have to decide where you would like to stay. But even 120AED roundtrip is still considerably less than £450. Plus DWC will be pretty deserted whereas DXB T1 can be an utter madhouse. So I would go with DWC in a heartbeat.