I've used this [link below] in the past, which is/was very good. Yardages were accurate [which is what you want] plus it gives you distance to front/centre/back of green pin positions. Good coverage of UK courses.
Not used it for a while [keep meaning to get out but not achieved it yet], but reading the reviews it's had several updates since I last used it - good or bad thing, I don't know. Might be others apps which are better, but not tried any.
Not sure if 'pro' version is worth paying for - never tried it, but maybe give this free one a try & see how you get on with it?
Disclaimer: I have no affiliation with this.