I did just this last year OP. When I decided I couldn't justify the cost of a new oboe although I have since spent £1200 on recorders .
I started with the Baroque Recorder Anthology, book 3 is for treble and billed as Grade 5-6. I also worked through '150 Classical Studies', Treble Recorder Technique by Alan Davies, The Modern Recorder Player by Hauwe and Advanced Recorder Technique by Helens/Bowman.
Some of the above was too easy but good practice. I do like technical studies though but they are not for everyone!
You can search by instrument on imslp.org for great free stuff which I do a lot of.