PowerEdge R710 ssd's

I would like to know if drive LED's will still work and if the drive failure Information still works as it should

This is an unknown. Best bet - other than seeing if others have had specific experiences with specific drives - is trying it.

Some SSD's do not properly display data used for LED's. Some SSD's show offline even if they are online (I have never heard of SSD's showing online when they were offline). Some will configure in RAID, some will not. It depends on the controller and its firmware and the drives and their firmware. Enterprise will likely have fewer issues. If you decide on consumer drives, don't do the low end consumer drives (Samsung EVO and Intel 320, etc.), use the higher-end "pro" series drives.

I have a couple of Intel S3500's that have been running in an R510 with an H700 for several years without issue. The LED's don't work and the controller gives alerts that the drives are not certified, but the online status and functionality has been fine.

see ,this is the issue which I am having is that these are all in production use so cant easily manage to have downtime to see if the drives work how we want them to. And for us we would want to know when a drive has failed .

But we don't have the budget to stretch to the dell supported ones which come in at around £800

You could get one only this FY, then another to mirror next FY. 

You could make the case to those that make budget decisions that more $$ is needed for a guaranteed solution, the alternative to that being that there may be some downtime as a result of incompatibility in the name of saving money. Put the responsibility on them, but you can't put a low-end consumer laptop drive into a server and expect it to work flawlessly, and those making the money decisions need to have those expectations properly set.

You could also put it off until the funds are there if there isn't the stomach to try it.