Wallpaper steamers do take a bit of practice, and are very dependant on the type of paper that has been used. If you have lots to do I recommend an angled scraper, such as.
www.wickes.co.uk/Professional-Heavy-Duty-Scraper---100mm/p/154805
(N.B. often the blade needs to be reversed before using, as they deliberately fit them with the blunt edge out) took me most of the house to realise)
Most steamers are "continuous", but there are some better ones with a trigger control which makes it much easier (Karcher do a wallpaper attachment for one of their steamers)
If you're doing the whole house, getting a skim coat may be cheaper than you think, cost varies hugely depending on where you are, but perhaps £300 a room. (bare in mind paint is usually cheaper than wallpapering and labour).
Talking of paint, if you're doing the whole house, and you're gutting the rooms, a paint sprayer is huge time saver.
Messy but fast, with a bit of practice, you should be able to spray an average sized room in under and hour per coat, raw plaster will need, 3-4 coats.
www.screwfix.com/p/wagner-w-690-flexio-630w-electric-paint-sprayer-220-240v/2884t
But you have to spend the time masking everything up, i.e. windows, light fittings, etc.
P.S. Buy a "hop-up" if you haven't got one!