What will happen if I Ice skate and my blades are dull? Will I be more at risk of not skating properly?

I have two pairs of Ice skates and I think the blades are dull on both pairs but I am not sure as I'm not experienced in knowing what is sharp and what isn't. Also, does anyone know if it's possible to have your blades sharpened at the rink just before you skate or do you have to take them in and pick them up days later? (I'm in the UK will be going to Riverside I &L. )