We present a robust battery energy storage system (BESS) management strategy for simultaneous participation in frequency containment reserve (FCR) and automatic frequency restoration reserve (aFRR) provision with market-based state of charge (SOC) restoration exclusively via intraday market. The study is motivated by the developments and harmonisation of the regulatory framework of European balancing markets and the rapidly increasing role of BESS in power system regulation. The proposed strategy involves BESS SOC restoration through scheduled transactions in the intraday market. It also includes reserve mode and recovery status management benefiting from regulatory alleviations granted to FCR providers that are qualified as limited energy reservoirs, and voluntary aFRR energy bid preparation process. Altogether, the management strategy is based on a worst-case activation anticipation approach, meaning that non-delivery of contracted reserves is under no circumstances permitted. Moreover, activation overfulfilment and FCR deadband utilisation are not allowed for battery charge restoration in line with the recent regulation. The strategy is particularly useful for balancing reserve providers that do not have options to restore the BESS energy content within their own portfolio, thus having to rely on wholesale markets, which can have significant lead time before trade delivery. Based on simulations, we first validate the robustness of our strategy in an extreme worst-case scenario and then provide case studies utilising power system operational data from Germany and Finland, showcasing the technical and economic performance of the devised strategy under realistic and diverse conditions. While our approach builds on the upcoming Baltic balancing market framework, due to the ongoing European balancing market harmonisation, it is applicable also to the EU markets in general.