I can see the advantages to some degree of using an umbrella company, some companies won't award you the contracts unless you do use one, however, I cannot understand why you would want to pay a company to get paid, to me they are just leeching money from contractors hard-earned.
Just buy an off the shelf company, or set one up for yourself. Reasonably cheap to run, you can do the accounting work yourself as you're unlikely to be turning over enough to need an audit, you do have to pay personal and employers nhi and paye on your own earnings, the usual thing is to pay yourself a low salary and make it up by paying a dividend. The problem is that HMRC are cracking down on the use of service companies as they can be used to evade tax and nhi, if you have several contracts with different customers you may be ok, there's a load of stuff on the HMRC website about IR35 (the regulation that applies) or an accountant will advise.
When I work I use Welcome to MyPay - UK leading PAYE Umbrella Company for freelance and contractor payroll they are very good. If you want to claim expenses such as accommodation,petrol,food etc you will have to set up a Ltd Company. You would need a good Accountant to determine if you come into IR35. If your contract is through an Agency you have to be registered with an Umbrella Company or set up a Ltd Company. The other alternative is to go PAYE with the Agency. If its only short term just go PAYE with the Agency the difference in take home pay is pennies. If you want further info PM me and I will give you my phone number and I will explain in more detail.
I don't work that much now but when I do it's generally short term ,but I do have lots of friends who are full time contractors and the problem they are having at the moment is are they inside IR35 or outside IR35. I should mention this is in the Aircraft industry where the use of contractors is common place.
My friend is going through this now with Agency he works for and his Accountant but it seems that from next April your end client will usually be responsible for deciding your employment status from April 2020. I'm glad I don't have to bother with this anymore.