I dont remember dates of first job

Hello. Unfortnetly I dont remember and didnt find any way to check the exact dates of my first job that was october 2015 - october 2016, i know dates +/- 5 days. Is it ok to write dates that may be not exact but max 5 days different than it was. and explain that in cover letter
Another issue, I found that stamps in passport are important. Most of my travels was inside EU so no stamps, but I had 2 situations that I went to Poland and stayed there around 2 days and travelled to Egypt (and another time to Dubai) and came back to Poland and from there after 2-4 days back to UK. Should I write on application on these dates Poland (as there is only option for one country) and pourpose : holiday (transit to Egypt) and explain in cover letter? or do it in another way? Thanks

1. Dates of jobs: it is sufficient to use estimated dates where necessary.
2. Stamps in passports: EU travellers as a rule don't have stamps in passport, you don't have to explain that, and you don't have to prove dates you were out of country. You prove residency by submitting official documents, such as P60s or council tax bills, other other official documents.