IPL and sun exposure

[Hazel]

I am currently having ipl treatments, due to have my 4 next week. my problem at the moment is I cannot use anything on my skin apart from distilled water (hoping that skin sensitivity is one of the things that the ipl improves), so can't use a sunscreen. I wear a hat as much as possible, but not going to and from my car etc. At what point does sun exposure become a problem in relation to ipl, getting burnt? getting a tan?, neither of which has happened but the weather here is really changeable, excellent one minute, horrible the next (typical Scotland), I find myself getting paranoid and keep asking my husband if I have the slightest hint of change of skin tone.

Thanks
Hazel