In my experience Freeview is certainly not worth chasing with large cash investments. Lost Film4 some time ago (not that brilliant anyway), never seen BBC4.
Best thing from my pov is Four+1 which gives the opportunity to sometimes avoid clashes.
If you want to see what you're 'missing', download the excellent Digiguide program which gives you a month's free trial (worth a subscription IMO) and will list as many channels as you wish.