Just got back from Asda (Wigan) and picked up a few shoes/boots for the lad. They had a large variety to choose from, for both girls and boys and loads of different sizes so worth checking your local. Checked online and they are also available online also. Few examples: -
Ballerina Pumps Price: Was £4.50 Now £2.25
Canvas Shoes Price: Was £5.50 Now £2.75
Canvas Boot Price: Was £6 Now £3
Printed Wellington Boots Price: Was £7 Now £3.50
Thomas the Tank Wellington Boots Price: Was £7 Now £3.50
Spiderman Wellington Boots Price: Was £8 Now £4
Sporty Lace Boots Price: Was £10 Now £5 (bought these)
Lace Up Casual Boots Price: Was £10.50 Now £5.25 (these were £5 instore - bought them)

direct.asda.com