Sart leads are available from £1 from your local pound shop, digi boxes from 15 quid in asda.
However - you aren't guaranteed to get freeview( I can't) but there are three further options
FreeSAT from SKY - cost somewhere between 75 and 150 quid depending on what offers Sky have at the time. This is obviously a statellite connection, this can be affected by very bad weather ( snow/ rain) but if set up correctly it is a very rare event. There is no monthly subscription with this offer but the number of channel is limited.
FreeSat - (No relation to the above) - if you had a sky digibox in the past and the wire is still in you can use this, if not it will cost ~ £60 for a dish. You then can choose standard definition( as per freeview and SKY and the terrestrial you currently watch) for about £70 or a high def box which can also receive some channels in high def but standard for most(Not all, think BBC.ITV and possibly C4 plus some fringe ones) for about £150. There is no monthly subscription with this offer
Of course you can also subscribe to SKY itself, usually you can get a free box with just 60 quid install if you take out the basic package at 16 quid a month. Considering you can also have free broadband with this ( up to 2 meg, 2 gig CAP) its a fair deal IMHO. If you want extar channels teh cost obviously goes up.
And its worth commenting that you can of course have any/all of the above at once. e.g.
my TV has built in freeview(which as stated I can't use due to the position of my house), I have Sky+ and I'm considering a freesat HD box maily for teh footy
.