[excession]

Gambling winnings are not taxed at all in UK.
Nor does playing poker count as a trade or job so I can't see that it would even be breaking the terms of a tourist visa. I think there is also a longer working visa available to Canadians but you would need to check that.
Any UK grandparents would entitle you to UK passport anyway - any EU grandparents would probably enable immigration to be honest.

Canadian citizens may be able to get access to free NHS healthcare - just check your travel guidebooks.. access to healthcare in the UK does not depend upon you being a taxpayer. If you are a tourist you might get cheap travel insurance anyway.

Cost of living is fairly high in most of the nicer cities but apart from a tax levied as a contirbution to local services (based on the value of the premises you are living in) averaging about £1000/yr there will be no other mandatory direct tax on you.