A) the best place for me to buy from an exchange (GBP) to multiple cryptocurrencies
Use localbitcoins to use for local exchanges related to Bitcoins. Use Bitbargain if you are looking for some better payment options available in your service.
B) where / how to hold my currency somewhere that doesn't have a lot of fees, and be able to monitor graphs and info on an app.
To hold, you don't need to do anything but just put it inside your wallet (sent from your exchange as you should never put it in an exchange).
Blockchain or Multibit are good, you could view some graphs on blockchain app.
C) be able to access my address and private keys.
Blockchain allows you to access your address but you need to import your private keys from other desktop wallets because now, it changes address everytime you use it once for privacy purposes.