Debbie
Welcome and well done for subscribing - it will pay for itself a hundred times over.
Alan's advice is very sound.
He has recommended two dealers and has quite correctly stated they both have good press.
What you have not indicated is whether you are looking for new or secondhand. I would strongly urge you to consider secondhand as there are some good quality MHs to buy at 50% or less than new. Also if you do not choose the ideal one first time the loss on changing it will be less.
Also look at the private sale market. There are lots of experienced and honest sellers who will not sell at the prices dealers offer them and a private sale enables both buyer and seller to win.
Dealers will offer some sort of warranty but as many people have found out it is not worth paying the additional dealers' prices just for this, as a 5 grand difference in price could pay for a lot of repairs, which if you buy a good=quality MH will not be required anyway.
You do not state, and may not want to, how much mobility you have, but if you were willing to do so it may help with advice on what considerations you should take into account. For example, whether your wheelchair is a folding or rigid one, because a rigid may need a garage or a rack on the back of the MH. If rigid and it goes in a garage the double bed over the garage will have a step access. There may be other layout considerations.
Certainly visits to a few dealers with a range of MHs to dealers will answer some of these questions. When you see some features of various models write down the ones you want AND the ones you definitely do not want. This will help you draw up a specification. I did this and showed it to dealers and also used it to research the private market and ask relevant questions when not advertised. I found that when I showed them a written spec the dealers took me more seriously and it saved time on both sides because they did not try to show something that was inappropriate.
Two important points to get into your specification is whether you want to use the MH in winter, in which case you need tanks in a double floor which is heated - very few British MHs are.
Secondly, 'payload'( i.e. what weight you can legally carry) - do not believe catalogue figures, which may not include extras. ALWAYS insist the vehicle is weighed and check that against its permissible weight.
How you use the MH affects what you need to carry within the payload. You used to camp on the bikes so you may wish to camp in wild spots so need the water tank full. If you intend to use campsites you can save weight by arriving with an empty tank and fill up before parking, likewise empty fresh and dirty tanks before departure.
I do not want to make the whole process look daunting but setting some parameters early on will make your search easier.
Good luck and come back to any of us for more advice.
Geoff