I think you should consider what you want before working out the best way to achieve it.
Do you need a quick sale, even though you get less money?
Do you need to sell it without hassle, avoiding dealing with scammers and timewasters?
If the answer to those is No, sell it yourself.
You are not offering a guarantee, so expect to ask 20% less than a dealer would for the same motorhome in your sort of price range.
You talk about
insurance and MOT. If it isn't parked on the road, you don't need either. Don't let that rush you into an unwise sale.
Personally, I'd either get it a new MOT now, or sell it with the promise of paying to fix any MOT failure items. Last motorhome I sold I said the buyer could have it with a new MOT or take the risk and I'd knock £1000 off the price, partly becasue I thought it would need a new exhaust for the MOT. He chose the MOT, and it passed with the old exhaust!
This was a few years ago. I'd advertised it on autotrader, which only got scammy sales calls, no proper leads.
I am pretty sure I then put it on an eBay classified ad.
The first person who came to look wanted to fit a towbar, which wasn't feasible on that van. The second person bought it.