How far in advance can you look up inter-European flights (easyJet, etc.)?

On skyscanner.com you can see flights up to one year in advance. For instance, I can see Oct 7 2015 but won't be able to see Oct 8 2015 until tomorrow. As an example I saw a one-way from Hamburg to London for $68 on Germanwings airline on Weds Oct 7 2015.

I would definitely use option 2 and fly into Hamburg, see Germany then fly to London for London/Wales and fly home from there rather than backtracking to Hamburg to fly home. It would all depend on the timing of your visits to your friends in Hamburg and London but option 2 is more efficient.

Most airline timetables are release twice per year, when the clocks change in spring (last Sunday in March) and autumn (last Sunday in October). The winter flights should already be released, so you should be able to book up to the last Sunday in March 2015.
Sometime around January 2015 they will release flights up to the last Sunday in October 2015. If you get in early as soon as the flights are released, you will get the pick of the bargains.

Easyjet is currently booking flights into May.

Interestingly I got an email from EasyJet today saying they have just released their summer 2015 fares which go to 6 Sept 2015. You may want to sign up for their emails.

Btw, you didn't ask but as I lined up for boarding my EasyJet flight from Paris to Venice recently the gate agent had everyone put their bag in the sizer including the lady ahead of me and the man behind who had the exact same bag.

I got that same email from EasyJet so their various customer lists must get the same treatment.

Thank you all. If I must go with Option 1, I should be able to leave my suitcase with my friend in Hamburg and just take my backpack for carry-on, so I may be able to bypass the luggage issue. If not, I'll make sure to check in my bag online to avoid higher-priced check fees at the counter.

Don't ignore British Airways. If you are flexible with dates/time you can get good deals. Sometimes, when you add up the extras charged by LCCs, BA costs can come out the same or cheaper. Plus they have a more generous luggage allowance.

What Linda said about British Airways (BA) is right, just be careful about which fare you ware choosing. They now have a range of fares which is designed to compete with the LCCs and includes NO luggage allowance.

You can do it either way...

@Linda, do you mean look at BA for flight(s) between England and Germany, or BA for my whole trip with multi-city stopovers?

Sarah - I was thinking about your European flights when I replied.

PS - to add to what Nigel said, the special fares are for flying without hold luggage the cost of which which is usally included in the price of your ticket. You can take up to 23kg cabin luggage (my hold luggage never gets to this weight!) with the special fares plus a personal bag.

http://www.britishairways.com/en-gb/information/baggage-essentials/hand-baggage-allowances

Thank you, Linda, and everyone else for your help!