In reply to FlavioL1989:
You would have to insure it as a panel van. To get it re-classified as a motorhome, the DVLA have a list of requirements which need to be met and one of those conditions is the addition of windows.
Sped restrictions, as far as I am aware, are for 3.5t and higher vans, not the smaller ones. For 3.5 tonners, If re-classified, you get to go an extra 10mph faster!
Sometimes its worth actually finding out what you are insured for. The insurance for my van was cheaper when it was a panel van, but when I re-classified it, it was more expensive as the contents of the van are worth far more now, though I had to stipulate the total cost to the insurance company. Thus, if anything happens, I will be insured for the cost of the converted van and not the un-converted panel van cost.
Post edited at 14:02