Julia; I am so sorry. I did not see your question come back up in my list and I forgot all about you. Please accept my humble appoligies.
I did some research for you and came up with a couple things. The first is a website with reviews of most all major brands of vacuums. Please click here to go to that web site. There are some very enlightening articles there.
The second is what I believe to be a very good deal and it has at least one stellar review by someone who gave it to their mother to use in her house cleaning business. I think you will find this unit enticeing.
Please click here to go to the web store that is selling this model.
Something that I should mention here is there is an "air purification system" (they insist it is not a vacuum) that I recall from years back. I once was in training to sell this unit. Never did though as Im a terrible salesman. It is the Rainbow Vacuum System. It is listed in the first link provided above.
My parents actually own this unit as do a few other people I know. The only bad thing about it is Im not sure if it is available in the UK. These IMHO are the absolute pinnicle of vacuums. They last forever plus 10 years if you have a son that is a good handyman like my mom does (pats self on back). They have owned their Rainbow for almost 30 years and although duct taped all over it still sucks up anything that isnt strapped to the floor. If they are available I strongly urge you to check them out. They are a bit pricy, but oh so worth it.
Thank you for the accept, and I again appoligise for forgetting you.
Best regards, XXXXX XXXXX Smithy