Yes, they're out in the UK, Hasini. The retail price is apparently £41, but no way would I pay that. S4 is currently £29.99 and S3 £24.97 on Amazon UK, but you could probably do even better than that on the high street with a little shopping around.
I haven't bought anything on the high street for years, but last time I did the best place to shop for DVDs was WH Smith or music stores like Virgin or HMV.
The UK comes under Region 2 for DVDs. Not sure which Region Sri Lanka falls into. So you may need a Region-free DVD player in order to play any you bought here.
Since your mom will be in Scotland until January, perhaps it might be possible for her to order them online from Amazon and get them delivered to her here? Amazon would usually deliver well before January, I think.
LabRat