Hi Chris,
yes being locked up at the weekend could mean that you won't have access to association time or exercise etc.
I remember arriving at Feltham and feeling totally anonymous or even invisible. Food bought to my cell by staff who didn't acknowledge me, no access to fresh air, no introduction to staff, no introduction to other inmates, 23 hours imprisoned in my cell.
I was offered the opportunity on one wing (Kestrel I think) to shared accommodation or single occupancy - I selected single as I'm a private person.
Certainly take a book with you. It may be confiscated initially but you will receive it back on release or when it's been security cleared. Obviously, if you can retain reading material it will keep you occupied.
The transfer from Court to prison is a hideous experience. The prison van or 'sweat box' is confined, claustrophobic, hot and anxious inducing because of your destination. Keep calm and try to remain positive.
On arrival DON'T think about where you want to be, it merely prolongs the agony of incarceration. Focus on your current environment and ALWAYS attempt to extract positives - education, work, skills, reading those books you've never got round to reading (I highly recommend Hugo's Les Miserable).
If you boycott the bravado and aggression of Feltham, you may be able to complete your sentence via electronic curfew for the final few months. Any sentence below four years can be subject to this opportunity - Boy George for example.
Chin-up and take care.