Did you get one in the end OP?
For my twopenethworth I would say try before you buy and if you like it, go for it!
Had motorcaravans for years and yes they are expensive (a half decent new one is in the region of £100k nowadays) and time consuming to own but the freedom is great.
We keep ours on the driveway (which is one way of keeping costs down) plus it means you can just pop out to it if you want to put something away (clean washing etc).
We never unload, it is left fully equipped (apart from perishables) so when we go away (which is most weeks) it is as easy as loading the fresh food and away we go. We can empty water & toilet at home if we haven't been to a site
We tend to use CAMC sites only, not the cheapest but always nice sites with good facilities and usually in great locations. At times we use CL's and our onboard facilities.
Other times we don't even stay over and we just use the van as a base for a day trip. We have lovely countryside on our doorstep and will often just drive for 30-mins and then park up (suitable locations for a 7.5m van can sometimes be awkward to find but you soon learn) and take the dog for a walk. Best bit is that you come back, rest your feet, have a cuppa and a bite to eat and then out you go again for another wander. Great having all you need (Inc toilet) with you, plus the dog is well walked!
Cost wise it can add up but in our case this is our lifestyle so no other holidays etc have to be factored in.
Purchase (as already stated, £100k for a decent sized one if you are looking at new). Servicing & insurance don't have to cost more than a normal car but there is the annual habitation check (not compulsory but required for warranty) and when required, tyres can cost more. Check your roadside assistance as "normal" policies won't cover anything over 3500kg (which many vehicles are). Your driving licence may restrict you to the maximum weight you can drive but if you have a C1 entitlement and go for a larger van, your annual VED will be less! Things like food, gas etc we don't factor in as if we are away we aren't using anything at home. Likewise fuel, we accept that to go away we have to buy fuel.
Site fees vary, as I said we use CAMC which are not the cheapest but they generally mean a decent location.
There are different ways to enjoy your motorcaravan and of course you can do it on a (much) smaller budget but each to their own and after the house, our vans have been the next most significant purchases we have made.
They are not investments as such (apart from the COVID spike they still cost more to buy & run than you will get back) but for us they are an investment in happiness.