Gonna separate your question - you can buy specialist rose food easily from garden centres, etc., such as Toprose. Choisya and bay tree, you don't say whether they're in pots or not - if they're in the ground, rake in some Growmore around the base of the plants - you can also do this if they're in pots by turning over the top of the compost and stirring it in, then topping off with a bit more compost.
Not sure what you mean by compost - do you mean potting compost or garden compost for the soil? If you mean for potting, multi purpose will do, but John Innes No. 2 would be better, or a mix of the two. Roses, unless they're patio roses, do not do well in pots.

Thanks for the reply and sorry for being a bit vague - all the plants mentioned are potted and I just wanted to check whether any of them required any specific compost e.g. non peat etc. I will add the rose food and also the Growmore but wanted to know in the meantime that a good multipurpose compost wouldn't do them any harm, in particular the newly-acquired bay tree.
Thanks again.