Lots of good advice esp from Faye. Important to focus on the child's needs not your needs. As others have said walkers are a particularly short lived and space consuming toy. Once the child is walking it won't be used again and they are not recommended as an aid to walking these days.
Most modern first world kids are drowning in toys. One family I know continually struggles with the overabundance of gifts from one gran despite many, many discussions. They have tried to give the gifts to charities after Xmas but even the charities refused brand new unopened toys because they so have so much donated after Xmas. The sad reality is that it all just ends up as landfill. Ditto the profusion of stuffed toys around. Apart from a couple of special cuddly toys no child needs or wants 100+ sentimental furry creatures that the gran buys almost every time she goes shopping. No use to the kids and bad for the environment.
For a one year old you can't go past a box of Duplo which connects with Lego as they get older. It has so many learning benefits for little ones and is perennial. When they visit my gc still play with my children's Lego saved from the 70s and love their Lego collections at their places.
Do you feel guilty if you have a lie in??



, ask your DS for other options. Is he aware you have the voucher (I won't ask which store)? There are lots of options, also I usually buy for next age group up as they grow out of toys at that age.