Depends what kind of beer you like to brew. Being in Kent shouldn't make much difference, it's obviously a good place to grow hops, the only caveat is that the remaining 1000 acres or so of commercial hops represent a good reservoir of hop-specific diseases, which are more likely to be a problem for older, more traditional varieties than for more recent ones.
Without wanting to teach grandmother to suck eggs - the varieties available as rhizomes are limited, you can't get any patented ones (ie just about everything released in the last 20 years or so), and a different climate means that the flavours of UK-grown hops can be very different compared to the same variety grown eg in the semi-desert of the Yakima Valley in the US. And as Cwrw666 notes, you get far more vintage variation in a British climate, you really need blue skies to bring out the fruit flavours, whereas cloud tends to make things go more earthy.
So your other US alternatives to Cascade are Chinook and Centennial, both solid choices as long as you don't expect the intensity of the commercial US-grown ones.
As far as "less traditional" English varieties, there's two obvious groups - the "blackcurrant twins" of Bullion and Bramling Cross, and the "revivals" - Ernest and the Keyworths, particularly Keyworth Early. The only problem is finding them, Aplus have had them in the past and it may be worth asking them if they have any even though they're not on the website.
