Ah sky being ahem somewhat economic with the truth as usual....)
A Sky box without a card in it will give you all the free channels. BBC1 2 & C4 should work fine, (ITV & C5 depend on which area you are in - if your location in Yorkshire is accurate you wont get C5 on the epg without a card).
Many of those 240 channels will be fairly low budget unwatchable stuff, religious, slapper on a sofa, or foreign language stuff for the Asian diaspora)
A card will give you C5, Fiver Five US, the +1's of the latter two and Sky 3 - plus possibly Liverpool TV which was ftv but I dont know what the current situation is. Plus it will regionalise your box to the correct BBC & ITV selections - with no card you get BBC London & Central West!
Freesat gives you a selection of the channels available on a FreesatfromSky box, (those that have signed up to the FS epg system). However most of the rest can be tuned in using a (somewhat fiddly) alternative tuning process.
To be honest I suggest you go down the local boot fair over the weekend and see if you can pick a box up for a couple of quid. At the end of the day if it doesnt do exactly what you want you havent invested much in it
Most of us started with cast off second hand kit - I started with my parents old analogue kit when they upgraded to digital - the box dish and assorted lengths of ropey old coax made the long journey up the M6 as they had strict instructions not to let the installer take it away - the dish is still in use today as our Sky digital dish!)