I would second making your making your own lap robe. A plain color with blending or contrast edging is pretty simple to sew up. The velcro closure is only a few more stitches! I made our first laprobe this same way. No fancy stitches needed! Hope you can sew, makes life lots easier.
Choices of fabric weight might be chosen for the season, cold or warm. No way I would want a heavy laprobe in 80F temps! Neutral colors, no pattern, will work wth most choices of blouse,
slacks and jacket. Length no longer than ankles, you don’t want to trip on it while wearing it. Even a bit shorter is still fine, it can end up longer when seated. Not real tightly wrapped when seated in the carriage, in case you need to exit quickly. The laprobe usually is tucked under your seat but not tight around your legs.
Elastic under your hair secures your hat against wind, slippery hair, unless you can do up a bun to anchor hat with a long hatpin! Helmets are ALWAYS legal in ADS shows, good in timed classes.
No-slip soles on your shoes in the carriage. Fancy ladies shoes, leather soles, raised heels can slip when foot needs to stay in place.
Gloves are traditionally ALWAYS brown, never black Old Victorian custom of wearing black gloves shows you in mourning dress, someone died. In practicality, brown leather gloves don’t usually bleed stain color if wet (rain or sweat). Black leather gloves will bleed black when wet to stain hands and clothing. There may be black leather gloves that don’t bleed these days, I just have not seen them yet.
Pack your smile, always a good item at a show!