I'm keen to have a fruit tree in our garden, and my mind turned to what's really the default UK fruit tree: the apple. The thing with apple trees, though (and in fact many fruit trees), is that if you want to get actual fruit, the tree needs to be fertilised. For the vast majority of apple varieties, that means having at least one other apple tree, of the right pollen group and which blossoms at the right time, planted somewhere fairly nearby. In an orchard, a big garden, or even in an allotment where you can count on other allotmenters also having apple trees, that's fine. If, on the other hand, you have a tiny garden like mine, one tree is going to be pretty much all you can fit in.
Happily, in this modern age, you can get self-fertile apple trees; that is, trees which will pollinate themselves. Even so, they'll do better (crop more heavily) if pollinated by another nearby tree, but you'll get a crop anyway. For my purposes, all I want is a few eating apples, and a tree to sit under, so that'll work fine for me.
The choice, though, is a bit limited — here's one list*, although note that some of those (the starred ones) are only partly self-fertile, so best to avoid if you don't want to rely on having another tree in the vicinity. In my case, it's limited further by the fact that the apples best-liked in our household are the Cox/Russet kind of axis. I couldn't find any self-fertile russet types, but here is my list of self-fertile Cox-types:
- The classic Cox, self-fertile version (also available from Trees Online). Upsides: well, it's a Cox! It's the classic English dessert apple. However, it's also a bit tough to grow, and can be disease-prone. It needs a 'relatively cool maritime climate', which is fine in the UK, but I confess that the disease-prone-ness puts me off a bit. I want a tree I don't have to struggle with. Ripens October-ish.
- Red Windsor (also available from the Orange Pippin shop). Advantages: easy to grow, reliable, disease-resistant, heavy cropping, apples picked over several weeks (ideal for a tree for home-eating, as it means you don't get a glut). It has a Cox's ancestry, but is a red variety. What I haven't found much information about is what it actually tastes like, which puts me off a little. (The Orange Pippin folk are sadly unhelpful.) Ripens early September.
- Sunset. Another Cox-like apple, disease-resistant and crops well, but the flavour can apparently be variable, and less flavoursome than Cox's in a bad year. I'm in this for flavourful apples, so not a variety for me. Ripens mid-September.
- Winston (also available from Victorian Nursery). Some people seem to claim that this is a russet, but its parents are Cox's and Worcester Pearmain, so... not really. Keeps well, disease-resistant, easy to grow, and has a Cox-like flavour. Ripens in December, but sweeter if picked in January.
For me, I think it's a toss-up between Red Windsor and Winston, with a probable bias towards Winston. I shall consult the rest of the household.
A quick note as well on rootstocks. M27 will give you a very small tree (up to 2m), but unless you're seriously space-limited or growing in a pot, you're probably better going for M9 (full height up to 2.5m), which is a little bigger and significantly more productive. Both M9 and M27 require permanent staking. If you have the space, M26 is bigger still, and MM106 a decent standard size, growing to 2.5-4.5m. For my 40m2 garden, I'll be choosing M9 as a good compromise between size and productivity.
* I have noticed some disagreement between different lists on whether or not particular apples are self-fertile. I recommend cross-checking a couple of sources before buying.