Thanks for clarification -
That is unfortunate if attitude and carelessness affects her writing. And obviously at secondary school, virtually all subjects will require to be written up, even Sports or Games probably on some occasions!
As I said, you should easily be able to find a tutoring agency, that will provide tutors for all over London. Make sure you read all the 'small print' and check as thoroughly as you can exactly what levels they teach to, whether there is any kind of 'guarantee' of progress, how long a contract or commitment lasts, can you 'get out' if it isn't working for your child.
But a tutor isn't necessarily going to be able to 'cure' a lazy attitude.
Have you tried to get advice at her school? Is there a pastoral person, or Head of Year or House, who can encourage children in such circumstances? Your child can't be the first to be like this; maybe they keep Yr7 in mixed ability until they settle down, and teachers really get to know pupils. I would expect from Yr8 that English and Maths should be streamed by ability, even if other subjects aren't.
Do you know what her attitude to a tutor is, or will be, or have you not got around to asking her yet?
If you do find a suitable agency or tutor, I will have a look at the details, if that is any help to you. But obviously, the decisions must rest with you and DD.