We want to adhere to the room-sharing guidelines to reduce SIDS risk but there is no room on the side of the bed. We can comfortably fit the cot at the foot of our bed. Does placement of cot make a difference to SIDS risk? Is placing the cot at the foot of our bed (visible from bed) just as safe as placing it next to the bed?

It’s great that you’re aware of the Red Nose safe sleep recommendations, including sleeping baby in their own safe sleep space in your room for the first 6 months, if possible.
https://rednose.org.au/article/what-do-the-safe-sleep-recommendations-mean

The first 6 months is considered a “critical developmental period” for all babies in relation to safety in sleep to reduce the risk of Sudden Unexpected Death in Infancy (SUDI & SIDS):
https://rednose.org.au/article/why-are-safe-sleeping-recommendations-so-important

We are not aware of any evidence to show that having the cot in a particular position in your room increases or decreases the risk of SIDS. Having the baby within hearing and sight of you seems to be a protective factor.

Some things you may wish to consider include positioning the cot away from open windows and dangling cords, ensuring that any nearby heavy furniture or wall-mounted TVs are securely fastened. More information here:
https://rednose.org.au/downloads/RN0407_22_Cot-to-Bed.pdf
https://rednose.org.au/article/setting-up-a-safe-nursery-what-products-do-you-really-need

And it is always very important to follow the 6 safe sleep recommendations and ensure baby has a safe sleeping environment:
https://rednose.org.au/article/red-nose-six-safe-sleep-recommendations
https://rednose.org.au/article/what-is-a-safe-sleeping-environment