I would suggest that you take time out to go to one of the mobility shows. In April there is one in Manchester and I think June at the Peterborough Show Ground. This will enable you to try out as many power chairs as you like and talk to manufacturers and suppliers. You do not have to buy and can just have some fun.
My supplier Bromakin has a wide range which can be tried out, new and used. They guarantee the used chairs and will turn out to service if required. My own chair started out as a new Beetle and when I wanted something more powerful we kept the top which suits me having a drop down control, soft seat and active back and obtained a used Puma base with its bigger wheels and more powerful batteries. In effect I am still using a chair which is entering its 7th year of use.Suppliers vary and I would try to find one in your region which has a good record of service and who are happy for you to visit and try out what they have in stock.
My chair is a heavy weight and I would not use it in the house. I still ride up mountains (even if a bit limited) but then my husband has the task of loading and unloading my chair (part dismantled) into our vehicle which is quite a job. So basically, you need to first sit down and take stock of what would meet your current requirements. As said previously, there is no one fix but also it is costly.
You could enquire about a power pack for your existing manual chair if vibration and pressure do not cause you a problem.