Not sure how many TVs have a sound input - some have a sound output to feed into an Amp and speakers (or a 3.5mm socket for headphones), but not all.
Also, in my (albeit limited) experience, some of the modern TVs will distort the sound if you have the volume up a bit... I have 42", 40", 32" and an assortment of 24" sets (that get used with various computers, plus Android tablet, PS3, FreeSat, Freeview HD, etc)
I'm using a separate hi-fi amp and speakers instead... but not one of the very costly amps at 700+ quid for AV... the setup cost me 250 for an Onkyo Amp, CD player, and Radio tuner and Wharfedale speakers (those alone would have been 100 quid).
Depends a bit on your laptop (some Tosh laptops are quite loud and have decent speakers in, like some Apple gear) but a 20-odd quid speaker system (2.1 so it has a sub-woofer for bass, and a pair of speakers) would probably do the trick and you could place the speakers either side of the TV.
There are some reasonable reviews of Logitech speakers... sometimes found in computer sections of Asda, Tesco but also:
Altec Lansing BXR1321UK on Ebay 27.00
(possibly only 1)
LOGITECH Z323 2.1 PC Speakers at PC World approx 31 quid
LOGITECH LS21 SPEAKER SYSTEM 19.99 on Ebay
(or make a reasonable offer - eg 17.50)