@RickyTan I don't have the game Grand Prix Master myself, but from reading it should work with Kempston by default?
For Anteater, the remake released in 2021, it's a simple QAOP control set, with Space for start and fire. This is my anteater.opt file:
fuse_auto_load = "enabled"
fuse_ay_stereo_separation = "none"
fuse_fast_load = "enabled"
fuse_hide_border = "enabled"
fuse_joypad_a = "Space"
fuse_joypad_b = "Space"
fuse_joypad_down = "a"
fuse_joypad_l = "<none>"
fuse_joypad_l2 = "<none>"
fuse_joypad_l3 = "<none>"
fuse_joypad_left = "o"
fuse_joypad_r = "<none>"
fuse_joypad_r2 = "<none>"
fuse_joypad_r3 = "<none>"
fuse_joypad_right = "p"
fuse_joypad_start = "Space"
fuse_joypad_up = "q"
fuse_joypad_x = "<none>"
fuse_joypad_y = "<none>"
fuse_key_hold_time = "500"
fuse_key_ovrlay_transp = "enabled"
fuse_load_sound = "enabled"
fuse_machine = "Spectrum 128K"
fuse_speaker_type = "tv speaker"
Hopefully it helps.