This question got me thinking, would attending gliding lessons at the same time as my airplane training make me safer in a small plane or microlight?
Yes learn both, but... not at the same time. As Dave says, there are too many differences to be absorbing simultaneously. It's like a new airline pilot taking a type course on a Dash 8 and an RJ at the same time. It'll burn you out.
If all this is a hobby activity in the first place with no urgent time lines, drop the power training for now and go take a glider course. When you have your glider license, resume the power course (in most jurisdictions you get a bit of credit you can apply to the power license).
Absolutely no question that a power pilot who learned to fly gliders first, and especially if they became proficient in soaring, will be a superior power pilot. Without the engine there, you learn fine motor skills, control coordination, energy management and speed control, and the ways of the atmosphere, to a degree that a power student doesn't and simply can't. It also helps to remove a lot of the terror at the thought of dealing with engine failures. I learned power in 1975 and gliders in 1993, and wish I'd started on gliders first.
And you may just discover that soaring is the sport for you. You have to try it and get into it, and experience the incredible rush of climbing at 500 fpm in a thermal without an engine, that you found by trolling the sky, or spotting a hawk and joining him (and seeing him just look at you and carry on as if you weren't there), that may be a struggle to stay in or may be an easy elevator ride, maybe for 30 minutes in the air or 4 hours. No two flights are ever the same. The private owners at my club, on a good day, launch at noon or a little after, and come back at 3 or 4 or 5 pm.
Power flying is mostly enjoying operating a machine that takes you from A to B, or to go sight seeing, in really fun and novel way. Soaring is flying as pure sport; a game you play with the atmosphere. Like sailing a catamaran times ten, vertically. It may not be for you, but if you get into the game, it's like nothing else and it's worth going to find out.
Plus since you're aviating largely on solar energy and at non-profit clubs the instruction is free, it's somewhat cheaper lol.
No it will make it more dangerous. Gliders and powered aircraft have different flight characteristics. You will have learn how to handle two completely different machines. You will have to develop muscle memory for two different types of aircraft. The flight procedures for the two types of aircraft are completely different, different approach profiles etc. You will have a tendency to either handle the glider like a powered aircraft or treat the SEP like a sailplane, to stop this you will have to actively try to decide what to do rather than instinctively fly the plane.
Gliding is an excellent skill to learn and will improve your flying once you've got enough experience, but learning on two types that are so different is not a good idea.