Thank you both so much for your replies.
I am actually an accountant but not worked in practice for SO many years that my knowledge on things is more than sketchy.
Is this roughly correct:
IHT - if they didn't pay rent (which they wouldn't) it would be treated as a 'gift with reservation of benefit' so wouldn't fall under the 7 year PET rules but instead be included in their estate at date of death. However, the house is only worth about £270k and they won't have significant other assets so, even if the value of their house was included in their estate (even if it was in my name) IHT probably wouldn't be an issue due to the nil rate band? Is that correct?
CGT - the asset would become a chargeable asset from the date of my ownership, so my base cost would be the price paid/MV at that date. If I then sold it there would be a gain at that time chargeable on me being the sale price less that valuation I took it on at. Obviously I would have CGT annual allowances to use.
Care home fees - obviously I would NEVER be trying to exclude my parents house from paying for fees at the expense of them being put in a 'crappy' care home, compared to a nicer one if paid for. But just trying to protect against all their money being used and they end up in a care home that is no better than they would have been without money. I have read about the deprivation of assets rules, there is currently no indication of care being needed but am just trying to put best plans in place. I am also aware this is an emotive subject matter, with people having differing opinions.
Any further advice/confirmation would be very much appreciated xx