* All eyes on Brexit talks in Brussels this week * Retail sales take a hit in November * Ashtead rises on upbeat outlook * FTSE 100 up 0.05%, FTSE 250 down 0.3% (Updates to market close) Dec 8 (Reuters) - London’s blue-chip FTSE 100 index ended marginally higher on Tuesday as Britain and the European Union agreed on how to manage the Ireland-Northern Ireland border, while investors awaited a wider post-Brexit trade deal. The exporter-heavy FTSE 100 edged up 0.1%, partially helped by a soft sterling, after spending most of the session in the negative territory. While the Irish border agreement removes a major point of contention between UK and the European Union, all eyes will be on talks in Brussels this week as both sides attempt to close the gap on how to manage around $1 trillion in annual trade. “This doesn’t solve anything but it should create a better environment in which a Brexit deal can be achieved,” said David Madden, analyst at CMC Markets in London. “There is still a big risk if the deal isn’t achieved but there probably isn’t much upside if a deal is announced so traders are largely just sitting on their hands today.” The rhetoric on both sides has hardened since the talks faltered with just over three weeks until Britain completes its journey out of the bloc. The FTSE 100, however, is still on track to record its biggest quarterly gain since 2010 after being boosted by hopes that a working COVID-19 vaccine would spur a global economic recovery next year. Britain on Tuesday became the first Western nation to begin mass vaccinations and the first globally to administer the Pfizer/BioNTech shot. Meanwhile, the latest industry data showed British retail sales growth slowed in November as stores were shut as part of a new four-week lockdown. Among individual movers, rental equipment provider Ashtead was up about 2% after raising its annual outlook. (Reporting by Medha Singh and Shivani Kumaresan in Bengaluru; Editing by Saumyadeb Chakrabarty and Anil D’Silva)