Be very careful with insurance, while some companies have a very wide DOV clause, most companies require that the vehicle must have a substantive policy of its own for your DOV cover to be valid. If in doubt, you can get a daily policy for as little as £15 for a day's cover.
You must drive the vehicle straight from wherever it is now on private property to the MOT centre and back (and the test must be pre-booked). If required you're allowed to stop en-route at a petrol station (if you don't have enough fuel to get there), but that's pretty much it, there is no scope for any other sort of deviation.