The only kind of places round my way that keep olive trees in pots are dinky galleries looking to draw tourists in.
My understanding is that olive trees in the UK are expensive. Round here they're five euros a pop for a what's called a 'doblete', a couple of years old or so, ten euros for a four-year-old or thereabouts.
If I was paying upwards of seventy pounds for a tree, which is what a friend told me they cost in her local garden centre in Britain, and wanted to keep it long-term, I'd be putting it in the ground.
I don't want to upset anyone but olive trees are not bred to live in pots, unless you get a bonsai version. They're not specially bred like some fruit trees to live in containers. You will get heartache trying to keep one for years in a pot.
Olive trees don't mind the cold that much and they don't even mind winds (we get 60-100 kmph winds for days not to say weeks on end at certain times of year) but what they do need is sunshine for long periods of the year, feeding twice a year (nitrogen-rich in spring, P and K-rich in autumn), watering a bit in the early years and pruning hard to keep them in the shape you want and to clear out dead stuff. If you can give them that, you're laughing.
Olive trees live for hundreds of years, precisely because they can cope with extreme conditions.
I wouldn't keep one in Manchester (not enough sunshine), but you could start up groves in Cornwall! Don't expect to make money off selling the fruit, mind. Farmers round here get 27 cents a kilo for their finest olives, less for olives sent for oil.