That depends on when you want to eat the apples. Most kinds will grow on chalk as long as you thoroughly prepare the soil to give the roots some depth of soil to grow into.

Recommend Spartan apples - sweet/sharp, very juicy, crisp. Check out ornamental-trees at leominster for varieties including step-over, espalier, trees etc. They also do bare root, potted and air pots.

Shows how tastes differ. I do not like Spartan at all.
Early one would be Katja (Katie) or Discovery, but there are hundreds to choose from.

If you are only having one check whether it is self pollinating, unless a neighbour has one close by.

We have chalky soil and grow lots of different apple trees quite successfully. For an eating apple, I would choose James Grieves every time - wonderful flavour, but as Owdboggy says, tastes certainly differ - I don't care much for Spartan, either!

Here we go again. I like James Grieves taste, but in the end we dug it out here as it rarely produced decent fruit as it was very prone to Scab in this garden.
Agree about needing to check up on fertilisation. Best to plant two compatible trees really.

we used to grow a james grieve apple on very light soil, and always had a good crop with no codling moth/scab or other problems etc; although we did have to water it a lot in the summer. we have now moved to very heavy soil with river mud just a few inches deep so we are a bit worried about scab. do agree though it is best to plant two compatible trees.

if you've only room for one tree I'd recommend a 'family tree' we inherited one 25 years ago and it always crops well with 3 different varieties on the same small tree-- they are grafted with varieties that pollinate each other

Also which colour of apple do you prefer? Green or Red? We have Greensleeves which is a lovely sharp, green eating apple, mid season.

That's a very, very good idea, Pamg. Can you order them from anywhere that lets you choose the varieties that are grafted together, or do you have to go with the nurseryman's choice?

No idea Gattina I don,t know our varieties but theres one on there which is small,red/yellow with yellow flesh that has to be eaten straight from the tree, do that and its crisp,juicy and such a lovely almost citrus flavour, leave it in a fruit bowl for just a day and it cotton wool......

I agree, Greensleeves is a lovely one, but don't know whether it needs a pollinater.