[littleblossom]

We would like a few apple trees and wondered if anyone could recommend any sweet high yield ones please?

[sunshineband]

I can tell you what we have, and we rather like them 

At the plot

Braeburn, (late fruiter) James Grieves (early fruit) and a Golden Russett- they are all compatible for pollination times

At home

Grimes Golden (self fertile, late apple ripens at the end of October) Fiesta and Greensleeves - flower at the same time

All are easy to come by I think

[Yorkie]

No particular suggestions but, as Sunny alludes to, you need to ensure that they are compatible pollination-group wise.

Also, consider what size you want the eventual tree to be.  This will dictate which rootstock you buy your trees on.

A good nursery (either mail order or in person) will be able to advise you properly.

[littleblossom]

Thank you sunshine and yorkie 
We will need to go for M26, I think? as we dont have much space for them. My OH likes Braeburn, so that will probably be one of the chosen ones.
Now the 'daft bat' question     How can, for example, James Grieves - early, and Braeburn - late, be in the same pollination group?   

[Living in Hope]

After a huge amount of thought and thumbing of catalogues I have planed the following, but only last autumn so I can't vouch for taste but my criteria was to get the longest season possible for a site in the Peak Distrcit taking into account pollination groups:

So I have planted:

Laxton Epicure - earliest to fruit, pollination group 2
James Grieve - early fruiting, pollination group 1
Egremont Russett - autumn fruiting, pollination group 1
Sunset - autumn fruiting, pollination group 2
Adam's Pearmain - should keep to Easter, pollination group 2

Plus a Bramley's seeding - triploid and
a Crab apple (Everest) which has a long flowering season and may help with pollination.

[sunshineband]

Thank you sunshine and yorkie 
We will need to go for M26, I think? as we dont have much space for them. My OH likes Braeburn, so that will probably be one of the chosen ones.
Now the 'daft bat' question     How can, for example, James Grieves - early, and Braeburn - late, be in the same pollination group?   

They flower at the same time, but fruits on James Grieves grow much more quickly than on Braeburn

[littleblossom]

Living in hope - Wish we had room for as many! John Grieves seem popular so that may be one of the choices.
Sunshine - thank you for explaining that!