Thanks, does the link work? The page keeps loading and loading for couple of minutes, but does not open.

Edit:
Yes it does, just takes a long time, maybe server issue on my side. T&C looks like the one we have already for the UK:

• The voucher can only be redeemed at www.lufthansa.com. The voucher is not valid in conjunction with any "Access Code" used to purchase already discounted fares.
• The voucher is intended for personal use only. Its resale or any other transfer to a third party is prohibited. In the event of a contravention, Lufthansa, or a third party authorised by Lufthansa, reserves the right to refuse to redeem the voucher.
• Vouchers are only valid for itineraries where all flights are operated by Lufthansa and Lufthansa Regional Partner (incl. Lufthansa City Line and Eurowings).
• The voucher can be redeemed between 26/04/2012 and 13/06/2012.
• Travel must be between 01/05/2012 and 30/06/2012.
• Only one voucher can be used for each booking process.
• The voucher reduces the tariff value of the ticket and cannot be used for fees, taxes, charges or other supplements.
• If the tariff value of the ticket is less than the value of the voucher, the residual amount can be deducted from the tariff value of other tickets bought in the same booking process
• If the value of the voucher exceeds the total tariff value of all the tickets in a booking process, the residual amount cannot be redeemed in a further booking process.
• The voucher is only valid for flights departing in United Kingdom.
• If a ticket for which a voucher was redeemed is reimbursed, only the reduced tariff value of the ticket – depending on the tariff terms and conditions attached to the ticket – is reimbursed.
• Vouchers and any residual values resulting from their use cannot be paid in cash.
• If the value of a ticket bought with a voucher is used as a down payment for a higher-priced ticket (e.g. towards a higher tariff), only the reduced value of the ticket is put towards the value of the new ticket
• Certain tariffs may be excluded from the use of vouchers.
• Vouchers may only be used for flight tickets, not for rebooking charges (MCOs) or excess baggage tickets
• The passenger receipt, which serves as an invoice for flight tickets, only shows the reduced ticket price.
• Lufthansa reserves the right to cancel a voucher at any time. Limit per promotion is one voucher per person. Lufthansa reserves the right to cancel the booking when the same passenger uses several vouchers.