Hello I'm new to this forum and need some advice. I'm just starting a new job where I will be traveling to and from Bratislava in Slovakia once a week for the foreseeable future. The companies agent has booked flights through CSA Czech Airlines. The flights out incorporate a change at Prague so it means getting 4 flights in total a week, however this is in economy (the business policy). My base is Heathrow so I was wondering what is the fastest FFP to get up the ladder to Gold or Platinum? And it may be a silly question but flying totally on another airline in the program and earning miles to another FFP is ok? Confusing question but there are no rules saying you must make at least one flight on your FFP a year or so??

Your advice would be most welcomed.

Welcome to Flyertalk, starnatty.
And welcome to the small group of CSA flyers on these boards.
Your FFP decision is a total no-brainer. Join the CSA OK+ programme.
4 flights a week mean that in 4 weeks' time you will make silver. From the fifth week onwards, you'll have lounge access in Prague and a decent chance at sampling the excellent business class product (complimentary space-available upgrades). Another 4 weeks, and you'll have Gold, giving you lounge access all across Skyteam and virtually guaranteeing your upgrades on Czech planes.
Enjoy the ride, and please avoid taking many flights from/to MAN, as I need the upgrades.