You can buy these beers in the UK, pretty easily.
If you like those, you should try the more traditional, less mass-produced versions.
Hoegaarden is a long-standing Belgian brand that was taken over by Inbev a few years ago and marketed to the world. It is what's known as a Belgian 'witbier' (white beer), and is flavoured with coriander. It's quite a different style from the German 'weissbier'/weizen (white beer).
There are strong German and Belgian beer traditions, but Holland is dominated by industrial beer like Heineken and Grolsch. So if you want a weissbier, you'd be much off buying a traditional German brand, rather than a modern cash-in. Have a look out for Paulaner, Weihenstaphener and Erdinger. All the supermarkets sell one or other of these.
I've not tried Grolsch Blonde, but at 3.8% alcohol I imagine it's terrible.
Duvel is sold in Sainsburys, and is a very fine Belgian beer, and is sold by both Asda and Tesco at the ludicrously cheap price of £1.28/bottle. Asda also do Chimay Blue, which is the best of the Chimay beers, at £1.60/bottle and Weihenstaphener @ £1.48.
Personally I like to an order of 12 bottles of each (this is their max limit), wouldn't use Asda otherwise.
If you want beers that haven't got the might of big brewers behind them, you will need to go with a company like [http://www.beermerchants.com/ Cave Direct]. Most of their beers are not available in supermarkets. The catch is you will pay more, typically £2+/bottle.
Beers such as St.Bernardus Abt 12 are better than anything you can find in supermarkets. Rochefort 10 (and its weaker cousins, Rochefort 6 and Rochefort 8) is a great beer, you can occasionally find it in certain supermarkets, but easily from an online beer specialist.
Majestic Wines usually have a cheap pack of Chimay with a free glass (the right glass makes a big difference to flavour), so it's worth going there.